Thermal Waves in Irradiated Protoplanetary Disks

Abstract

Protoplanetary disks are mainly heated by radiation from the central star. Since the incident stellar flux at any radius is sensitive to the disk structure near that location, an unstable feedback may be present. Previous investigations show that the disk would be stable to finite-amplitude temperature perturbations if the vertical height of optical surface is everywhere directly proportional to the gas scale height and if the intercepted fraction of stellar radiation is determined from the local grazing angle. We show that these assumptions may not be generally applicable. Instead, we calculate the quasi-static thermal evolution of irradiated disks by directly integrating the global optical depths to determine the optical surface and the total emitting area-filling factor of surface dust. We show that, in disks with modest mass accretion rates, thermal waves are spontaneously and continually excited in the outer disk, propagate inward through the planet-forming domains, and dissipated at small radii where viscous dissipation is dominant. This state is quasi-periodic over several thermal timescales and its pattern does not depend on the details of the opacity law. The viscous dissipation resulting from higher mass accretion stabilizes this instability such that an approximately steady state is realized throughout the disk. In passive protostellar disks, especially transitional disks, these waves induce significant episodic changes in SEDs, on the time scales of years to decades, because the midplane temperatures can vary by a factor of two between the exposed and shadowed regions. The transitory peaks and troughs in the potential vorticity distribution may also lead to baroclinic instability and excite turbulence in theplanet-forming regions.

39 pages, 15 figures The Astrophysical Journal, To be published

References in corpus (12)

• Spectral Energy Distributions of T Tauri Stars With Passive Circumstellar Disks
• Passive irradiated circumstellar disks with an inner hole
• Flaring vs. self-shadowed disks: the SEDs of Herbig Ae/Be stars
• Radial Flow of Dust Particles in Accretion Disks
• The effect of dust settling on the appearance of protoplanetary disks
• Turbulence in Accretion Disks. Vorticity Generation and Angular Momentum Transport via the Global Baroclinic Instability
• Effects of Dust Growth and Settling in T Tauri Disks
• A Survey and Analysis of Spitzer Infrared Spectrograph Spectra of T Tauri Stars in Taurus
• Spectral Energy Distributions of T Tauri and Herbig Ae Disks: Grain Mineralogy, Parameter Dependences, and Comparison with ISO LWS Observations
• Analytical protostellar disk models 1: the effect of internal dissipation and surface irradiation on the structure of disks and the location of the snow line around Sun-like stars
• Dust Growth and Settling in Protoplanetary Disks and Disk Spectral Energy Distributions. I. Laminar Disks
• Surface Outflow in Optically Thick Dust Disks by the Radiation Pressure

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